Investigating Tensegrity 3: Spheres (sort of)

Using the same principles as above (and a few websites describing how these structures work) I created a tensegrity sphere. Or more accurately, a dodecahedron.

This is different from the geodesic domes and sphere as they use pressurised air as their compression components. This structure is a pre-stressed tensegrity sphere, using straws and string. The strings are once again, a bit too loose for the structure but it still holds quite well. This is one method of creating the sphere in my architectural solution but the geodesic solution might be better for the large scale, or a combination of both. But this can be used for the base of the towers and other forms of morphing structure I might require.

Investigating Tensegrity 2: Structures

My next step in tensegrity models is to create a tower. This however proved harder than anticipated. My first attempt was a square tower constructed from the same components as above. The tower can be created by stacking two of the basic prism shapes on top of each other. To prevent two of the compression members touching, the stacked prism will have to be rotated and connected on the top tension cords. The idea was that the tower could stand on its own without having to have points locked in space because of the torsion force. The torsion force can be counter acted by making each prism have the opposite structural helix. This means the torsion forces have the same managitude but act in opposing directions. Adding the force vectors gives a resultant of zero (or it should if the tower is created properly).

However the created tower above looks very little like a tower. This was caused by my own mistake with measuring the string for the tension cables. I underestimated the amount the elastic properties of the string and thus they are too loose to keep the structure in appropriate tension.

For the next tower I created two triangular prisms from straws and string. Because of the problems I had with the string's elasticity, I used more compression components to insure the tower's shape and integrity stayed optimum. While this still is a tensegrity structure, it doesn't really require that many compression struts.

Above are the two prism components. When I tried to attach them to each other, the straws collapsed and both prisms were ruined.

From these experiments I have learnt that I need better materials. The tension component needs to be less stretchy, something like fishing wire. The compression components need to be stronger, preferably solid wood or metal rods. Also bringing up the scale of the model will make connecting the wire to the struts easier and make studying the forces in motion easier to view.

Investigating Tensegrity 1: The Basics

To get the most out of my tensegrity design, I had to educate myself on the principles behind the method. I decided the best way to do this way to create some tensegrity models myself. The first tensegrity model I have created is a triangular prism with three compression components (wooden coffee mixing sticks) and nine tension components (string).

This structure however cannot stand on its own. This is because all tensegrity structures at their most basic have a torsion component acting either clockwise or anti-clock wise (or left and right helix structure). Without this torsion force held in check the structure collapses. In this case I locked three points of the structure into fixed positions. Once this is done it can support weight and can act as a floor or platform. 

The Idea

The architectural solution I have come up with for our problem is combination of morphing and mobile structures. Using tensegrity structure’s ability to easily change shape and size, the site we house a group of these adapting buildings. These towers will accommodate any and all infrastructure needs the capital city will require as it grows. The residential needs and instead built in the centre of the site, in a sphere like formation. The structures grow together, the towers having a duel purpose as infrastructure and scaffolding for the living sphere. When the city has reached a critical point, the sphere (with people included) takes flight using roughly the same principles of a hot air balloon. This sphere will travel to an appropriate site along the railway line and settle down with it's new population, forming a new town.

I have also begun to investigate the political and communal systems required for a successful town and how to integrate them to the capital city site.

Beneath the sphere is a communal speakers amphitheatre, this is where decisions are made about the sphere as it is constructed. Only members of the sphere are able to have input and vote on these decisions. Over time, as the sphere is created, leaders will emerge from the community and these people will become the new council for the sphere once it leaves and the town it creates. The amphitheatre is still public so all can see what is happening in this community and not to segregate it from the capital city. Politicians can also visit it to speak and advice these new settlers.

Project 1 Presentation

Project 1 Statement

Canberra is rapidly changing from an artfully designed political hub to a heavily populated, economically important hotspot. The ACT is already has the second largest population growth in Australia (Bureau of Statistics, 2010). This growth is compounded by the introduction of a high speed railway network connecting the city to the surrounding major cities. This will make it viable for workers living in the dense cities of Sydney and Melbourne to live in the far less cluttered capital city. This abundance of space means more corporations are deciding to construct large facilities in Canberra and this will cause Canberra to have a stronger economic impact in Australia. This rapid increase of population will strain the cities systems and services. A solution must be found to this problem, and our mobile architecture strategy provides the answer.

In response to Canberra’s growing population, our strategy identifies the importance of a community focus towards the development of Canberra’s infrastructure. Our strategy will ensure the urban setting is enhanced across all spectrums of sustainability, including cultural, economic and environmental. This will be achieved by enhancing services through the implementation and incorporation of green infrastructure responsive and efficient public transport and affordable and mobile housing opportunities. The improved infrastructure will be compact, adaptable and efficient in order to maintain abundant green spaces and human-scale streetscapes to enhance the identity and presence of the nation’s capital.

To link our architectural solution to Canberra’s infrastructure, each architectural addition will be placed on key nodes in the public transport network. This will ensure our buildings are in the optimum area to help the growing population. The structure itself will be able to react and evolve to any situation that arises in the city such as to reinforce failing infrastructure, to house people of various socio-economic levels and to maintain the highest possible standard of living. Mobile solutions integrated into these structures will give them the best tools to adapt to these emerging challenges. These can include modular spaces, morphing structures and roaming services to quickly and efficiently create the required infrastructure to keep Canberra running smoothly.

Our mobile strategy will integrate into the existing fabric of Canberra, incorporating open, green spaces into the design. This will create new gathering areas, promoting the community hub theme of our strategy. For here our structures can help bring life to the new emerging culture while supporting the needs of the city and its people.

 Panels

Methods of achieving adapting structures

There are two mechanical methods of creating adapting structure that I have explored, tensegrity and pneumatics.

Tensegrity is a construction method using a compression based internal beams and supports balanced and held in place by an outer tension structure made from wires and cables. This is then covered usually by a fabric envelope. As the internal force grows and more pressure is pushed outwards, the strong the complete structure becomes. The benefits of this structure is it is quite lightweight and, depending on the complexity and size, it can be easy to assemble. This form of structure is also easily modified to allow morphing spaces. The internal structure can be built with pivoting connections so that when the tension wires are tighten or loosened, the space will change shape. Also whole sections of the structure can be moved as it is light compared to regular buildings.

There are a few examples of this sort of structure. The first is the instant skyscraper design by Farzin Lotfi-Jam and Jerome Frumar.

http://www.evolo.us/competition/instant-skyscraper/

This tower was designed to rapidly react to a disaster zone, to provide emergency housing and a main gathering point for vital resources. The structure is flat packed and moved to a site. It can either be built free-standing or attached to a ruined skyscraper, utilising it's core shaft into the structure. Horizontal cables are pulled by trucks at the bottom of the structure which applies the tension force, raising and locking the internal folded structure into place.

Of course, tensegrity buildings cannot be discussed without mentioning Buckminster Fuller, the father of tensegrity. His designs and plans utilised and expanded the field of tensegrity structure immensely. His most famous work is geodesic domes, which use principles from tensegrity engineering to build self supporting domes.

But his most ambitions idea was the Cloud Nine project. This project was to create a floating mini city inside a giant geodesic dome. The lift would be produced by the air inside the dome being slightly warmer (even as small as one degree). For the structure weight to be counter-acted by the warm air inside, Buckminster Fuller estimated the sphere would need to be a least 1.6km wide. The circumference of the floating sphere would contain the occupied structure while the centre would be hollow to contain the large volume of air. The sphere was designed to float and travel around the world when the surface became overcrowded or unliveable. This is a prime example of tensegrity structures with a mobile strategy.

Pneumatic mechanisms rely on manipulating pressure to inflate spaces, using either compressed air or inert gases. The inflated zones can be used to move parts of the structures or the zones themselves can be occupied (though if this option is used, breathable gases would be highly advised). Pneumatic systems in mobile architecture make the morphing of spaces very quick and easy. Different levels of pressure in the right zones can radically change the spaces in the building like in the SkinForm Project from masters architecture students from the University of Technology Sydney.

http://jakovich.net/skinform/index.php

Using pneumatic mechanisms combined with a tensegrity structure can increase the strength of the structure. By increasing the pressure inside the space, the tension components are put under stress. With the tension system under pressure, the overall strength of the structure increases.

So in conclusion, a combination of these, and other, mechanisms should be used to create the best adaptive architectural solution possible.